I have often heard the conventional wisdom that one should not use an X10 dimmer on a halogen bulb. But I have also read (through this forum), that it can be done if you bypass the halogen's dimmer.

So, is the problem really the dimmer that these halogen floor lamps often have? In other words, can I use an X10 dimmer for a incandescent floor lamp that has a built-in dimmer switch?

Thanks.

Eddie

I believe it's the type of transformer, electric/mechanical (inductive) or electronic that operates the lamp and not the dimmer. Depending on the transformer type, the dimmer is selected. With X-10, again I believe, I'm not 100% sure, depending on the type of transformer you can either use a dimmer switch or just the on/off type switch.

If I'm mistaken on any of this I'm sure someone will point it out.

I have one of the "walmart special" halogen floor lamps -- the kind that look like an upside down lampshade pointing at the ceiling. It has a two-level switch (off, low, high).

I use a standard X10 plugin lamp module. It works fine. The problem with Halogens is that they tend to have a short lifetime if they are below a critical temperature. The was I understand it, any material that evaporates from the filament should not plate out on the quartz tube. Presumably, when you turn them off, the filaments will cool faster than the quartz and it will plate back onto the filament. If the quartz isn't hot enough, it plates onto the quartz. So if you run the lamps at a low power level, you lose on lifetime of the bulb.

I haven't noticed any problems with this, and the X10 control works fine with the lamp turned on to either setting.

Joe

Here's the poop: A halogen bulb (not the fixture) is still an incandescent load. As long as the bulb is 120v, and not 12v (i.e., no transformer), any dimmer of the proper capacity will work fine.

The problem here is with cascading dimmers. Usually, as long as the lamp's built-in dimmer stays set fully on, there is no problem. Better still would be to bypass the built-in dimmer.

Joe is correct about dimming halogens, to a degree. As long as the light is used at full brightness occasionally, the reduction of bulb life is minimal. You should get better than 75% life.

There you go -- my fixture has an 120V bulb


Joe

Thanks for all the information.

I connected my floor lamp (150W incandescent bulb) to a LampLinc dimmer, leaving the lamp's built-in dimmer set fully on. It worked fine for a short while (minutes), but then the lamp brightness started fluctuating, down to off and back up to fully on. This behavior could be stopped by turning the lamp off and back on again. However, about 15 mn later, the lamp was dead (which was fixed by replacing the built-in dimmer). Is this expected or one of the exceptions to Larry's "usually there is no problem."

Thanks.

Eddie

Hi,
I have been reading this with interest as I am thinking about installing some small Halogen lamps and was planning on running them on a lamplinc. It sounds like I want to stick with a 120V lamp to avoid a transformer if I want to dim them.

As far as cascading dimmers I would expect this to be an issue if they are solid state or triac driven. Triacs turn off at zero cross of the 60 hz power line and need to be "triggered" back on again each half cycle. I would expect there to be an issue with syncronization of the two triacs in series. If one truns on and the other is not on at the same time there might not be enough of a (minimum) load for for the first triac to remain on.
I do not have first hand experience with this but this might be one explanation for what you have experienced.

Regards,
Ela